Piercing mill



18, 1928; 1,695,323 s. E. DIESCHER FIERCING MILL Filed Feb. 18, 1926 e Sheets-Sheet 1 FIEJ.

WITNESSES I I Dec l8, 192s. 1,695,323

v S. E. DIESCHER PIERCING MILL Filed Feb. is, 1926 e Sheets-Sheet 2 INVENTOR a. M WMM am.

Dec. 18,1928.

'5. E. DIESCHER PIERCING MILL 6 Sheets-Sheet 4 Filed Feb. 18, 1926 YNVE/VTQR Q b 6 6 M I WITNESSES &-%%

6 Sheets-Sheet 5 Dec. 18, 1928.

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Den 18, 1928.

PIERGING MILL Filed Feb. 18 192 6 6 Sheets-Sheet e Patented Dec. 18, 1928.

UNITED STATES PATENT OFFICE.

SAMUEL E. DIESCHER, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO S. DIESCHER & SONS, OF PITTSBURGH,:PENNSYLVANIA, A PARTNERSHIP CONSISTING 01? SAM- UEL E. DIESCHER AND AUGUST 11?. DIESCHER. 4 I

PIEROING- MILL. I

Application filed February 18, 1926. Serial No. 89,111.

The invention relates to mills for piercing billets to form hollow metal blanks for manufacturing seamless tubing by" the several methodsuscd in its production, it-being understood that the term mill is herein used to include a stand of piercing mill rolls and the mandrel mechanism associated with the rolls, and that the ternrbillet is used to designate any form of work piece, whether it be technically known as a billet, ingot or bloom. j

The object of the invention, generally stated, is to so improve the construction of piercing mills and their constituent elements that the outputs of the mills may be greatly increased and that billets may be more accurately pierced by them.

A specific object is to provide means associated with a seat of piercing rolls for so supporting amandrel and a billet to be pierced that the mandrel will properly enter the center of the billet and thereby avoid or lessen" the liability of eccentric piercing.

A further specific object is to provide an impro ved' mandrel carriage for piercing mills to the endthat billet-piercing and mandrelstripping operations may be simultaneously conducted with consequent increase in the output of the mill.

A still further specific object is to improve the constructions of water-cooled mandrels and their supports.

The means for attaining these and other ob;

jects are explained in the following description of the invention with reference to its embodiment illustrated in the drawings, of which Fig. 1 is a plan view of a piercing mill; Fig. 2 a vertical sectional view taken on the broken lines IIII, Fig. 1; Fig. 3 a trans-.

verse sectional view of a stand of piercing mill-rolls, the plane of view being indicated by the line. III-III, Fig. 2; Fig. 4 a View .to enlarged scaleof the working pass shown in Fig. 3; Fig. 5 a vertical sectional view of a mandrel bar carriage, the plane of view being indicated by the line V-V, Fig. 1, with the exception that one of its mandrel bar supports and its attached mandrel bar is shown as extending vertically upward; Fig. 6 a plan view to enlarged scale of one of the mandrel bar supports, portions of gear housings being in section'to show the construction of their conta ned gears; Fig. 7 a transverse sectional view a mandrel bar taken on the line VIII-VIII, Fig. 6; Fig.

9 a side view of a form of water-cooled mandrel bar and attached mandrel head; Fig. 10 a longitudinal central sectional View of the outer end of the mandrel bar and of the mandrel head shown in Fig. 9; and Fig. 11 a View corresponding to Fig. 10 showing a modification of construction in which the mandrel head as Well as the mandrel bar is water-cooled.

According to this invention, there is associated with a set of piercing rolls a mandrel carriage provided with a plurality of mandrel bar supports, the carriage being movable transversely of the line of feed of a billet through the piercing rolls, and the mandrel bar supports being .mounted for independent movements, preferably verti'cal, so that a billet may be pierced over a mandrel head on one mandrel bar while a pierced billet may be removed from another mandrel barQ Provision is made for properly cooling the mandrel bars and mandrel heads when desired, and for so supporting the rear end of a mandrel bar that during a piercing operation it is free to swinglaterally in all directions in accordance with exigencies of the operation. Associated with the piercing rolls means are provided for supporting at the beginning of a piercing operation in proper relationship with each other and with the rolls the forward end of a mandrel and the end of a billet to be pierced so that the mandrel head Willenter the center of the billet and thereby avoid eccentric piercing.

Having reference first to the general arrangement of the mill shown in the embodi: ment of the invention illustrated in the drawings, a mandrel carriage 1 is shown as being supported upon tracks, ways or slides 2' for ing in general of the Mannesmann type, but with curved faces, having their axes of rota-I tion inclined to each other in the Well known manner, and being adapted to be rotated by suitable driving connections (not shown) connected to the outer end of their necks.

The mandrel carriage is provided with a plurality of supports, preferably two, for mandrel bars 5 and 6, which supports are independently movable upon the carriage so that I one bar may, as shown in Fig. 1, be arranged between the piercing rolls for a billet-piercing operation, and another be swung to a osition for stripping a pierced billet from 1t. As seen in Fig. 3 the upper portions of the roll housings are flared outwardly to permit the mandrel bars to be moved laterally 2 while being placed in or taken from billetpiercing position. These housings are of rigid construction, bolted to ether as indicated to resist the thrusts of t e rolls, and the rolls are mounted inthe housings for lateral movements, both for adjustment and to spread the rolls in. case cobbles are struck.

The detail construction of the mill will now be explained, reference being first. made to certain mandrel and billet supports associated with the piercing rolls, and thereafter to the mandrel carriage and its mandrel-bar sup orts.

onsiderable difliculty has been .heretofore experienced in causin a piercing mandrel head to always enter t e center of a billet to be pierced, and when a head does not enter the center of the billet, the billet becomes pierced eccentrically throughout all or 'a portion ofits length. To overcome this diificulty means are arranged between the piercs1des of the piercing pass so that ing rolls for supporting at thebeginni-ng of a piercing operation and in'proper relation, to each other and to the rolls the forward end of a mandrel and the end of a billet to be pierced, it being understood that the term mandrel is herein used to designate the mandrel bar and head .as a unit. The preferred means for this purpose is a billet-supporting roller 10 (Figs. 2-4) and a mandrel supporting bracket 11. Roller 10 may take the form ofa similar roller disclosed in my United States Patent No. 1,586,975, and may, 1n addition to supporting theend of a billet in proper relation to a mandrel, also unction as explained in. that application. The roller is mounted on a horizontal axis, transverse to the axes of the piercing rolls, in vertically adjustable bearings 12 arranged at the scale will not fall upon the bearings. Y j

Mandrel-supporting bracket 11 is prefer ably rotatably mounted to swing to and from its operative position, and'to such end it may be rovided with hubs 13 engaging the inner en of the bearings of billet-supporting roller 10. Normally, the weight of bracket 11 tends to swing it to its lower inoperative position, although its weight is p-referably' counterbalanced in part by a weight 14 attached to the bracket on the opposite side of its axis of rotation. "For moving the bracket upwardly to its mandrel-supporting position indicated in Fig. 2, the bracket may have a lug 15 provided with an adjusting screw 20, the lower end of which is adapted to be engaged by the upper end of a movable .rod 16. This rod is provided at its lower end with a piston or head 17 arranged in a cylinder 18, to and from which pressure fluid may be supplied and exhausted through a pipe 19.

At the beginnin of a piercing operation pressure fluid is admitted to cylinder 18 to move rod 16 upwardlyto raise bracket 11 to its mandrel-supporting position. The position of adjusting screw 20 is such that, when piston 17 is at its uppermost position in cylinder 18, bracket 11 is in its required position 11 to be moyed downwardly out of the path of the pierced portion of a billet, it being understood that even although pressure fluid does not then act to hold bracket 11 upward- 1y,'the bracket is not, because of the friction between it and the mandrel head, free to swing or move downwardly. It therefore requires the movement of the billet to move bracket 11 out of the path of the pierced portion of the billet. I L

Having reference now to mandrel carriage 1, it has already been explained that it is mounted upon tracks or ways 2 for movements transversely of the line of feed through the piercing rolls. For effecting such movements, the lower portion of the carriage may be provided with lugs 25 (Fig. 5) between which there is arranged an internally threaded sleeve 26 which receives a threaded feed screw 27 adapted to be rotated by a reversible motor 28 suitably connected to the outer end of the screw. By operating motor 28 in one llO tively. The construction and operation of each support is the same and each is provided with like independent means for rotating it on a horizontal .axis to swing its attached mandrel bar to and from piercing and stripping positions. The construction of mandrel support 31 will now be explained, it being understood that what is said concerning it applies likewise to support 30.

Support 31 is mounted for adjustment longitudinally in a housing 32 (Figs; 5, 6 and 8) provided with trunnions 33 and '34 rotatably mounted in brackets 35 and 36 supported by carria e 1. Trunnion 34 has keyed to it a gear 37 w ichmeshes with a pinion 38 (Fig. 1) attached to a shaft 39, to which there is also attached a worm gear 40 (Fig. 2) meshing with a worm shaft 41 attached to the rotor of a reversible motor 42.. Through this train port so that the bar may rotate upon its longitudinal axis, and may also move laterally in any direction according to the exigencies of a piercing operation, and means for supplying water or other cooling fluid through the support and its attached mandrel bar.

For adjusting mandrel bar support 31 within its housing 32, and also for connecting the support to the housing to resist longitudinal thrusts and pulls upon its ,attached mandrel bar, support 31 .is attached to housing 32 by means of a plurality of screws 45, each of which engages an internally threaded nut 46 secured in a lug 47 projecting laterally.

from and formed integrally with housing 32, the several nuts 46 being held in these lugs by means of a ring 48 attached to housing 32. 'The outer ends of screws are provided with pinions 49 each of which ,meshes,

-' with an external worm Wheel ring 50 rotatduring a piercing operation. Bearing isably mounted upon the forward end of support 31. Meshing with ring 50 there is a worm shaft 51 attached to a rod 52' adapted to be rotated by a hand wheel 53, The rotation of worm shaft 51 by hand wheel 53 causes ring 50 to rotate upon support 31, and such rotation of this ring rotates pinions 49 to cause screws 45 to move inwardly ,or' outwardly of lugs 47' to move support 31 with relation to housing 32. i

Within housing 32 there is a water-cooled thrust bearing sleeve 55 provided Jwith a series of inwardly extending rings 56, be-

tween which there are disposed rings57 pro-'- jecting outwardly from a central thrust block or hub 58. Between rings 56 and 57, there is an extended layer of bearing metal 59 so that block 58 may rotate within thrust bearing'55 in response to the rotation of a mandrel bar formed of two or more parts laterally applicable to block 58 when the latter is, r-e

moved from support31, and this bearing is held at its ends in its indicated position by a ring 60"bolted to support 31 and by an inturned flange 62 forming a part of support 31.

with a spherical bearing 65 for receiving a spherical head 66 formingopart of a mandrel coupling member 67 which projects forwardly of block 58 and lies in the forward lars 71 projecting outwardly packin'g'gland attached to casing 85; Supply i the inner end of mandrel bar 6, which bar is attached to the coupler by means of a ring 69, through which bolts extend and engage the coupler, such bolts also passing through 001- fiom the inner 70 end of mandrel bar to cause the coupler to rotate with the bar;

The outer end of coupler 67 is provided with a flange 75 for receiving a bearing ring 76 the outer face of which bears against a ring 77 attached by bolts '78 to support 31. So that the outer end of coupler-67 may inove laterally in any direction which it may be caused to move by a piercing operation, the outer bearing face of ring 76 is of spherical form, the radius of curvature of which is struck from the center of spherical head 66 at theinner end of the coupler. lVhile these lateral movements of the mandrel bar are made effective from the center of spherical .85 head 66 of coupler 67 axial rotation of the -mandre l bar is transmitted from coupler 67 to block 58 by means of lugs 79 which project laterally. from coupler 67 and are arranged between lugs 80 projecting forwardly from blocks 58, there being sufficient space between these interengaging lugs 79 and 80 to permit of suchlatera'l movement as may be imparted to the coupler by a piercing operation. At the outer end of. the coupler provision is made by a space 81 between the inner face ofring 77 and the outer face of bearing 76 to permit lateral movement of the outer end of the coupler, and for the same purpose there is an annular space 82 between an inturned flange 83 ofring 69 and an outwardly turned flange 84 of ring 7 7 such overlapping flanges being provided for excluding ,scale,'grit, etc: from the bearing formed between rings 76 and 77.

As far as concerns some features of the invention the mandrel bar need not be cooled, or if cooled water or other cooling fluid may be led to and from it in various ways. ,However, when the mandrel bar is cooled, coolin fluid 1 1' ispreferably led to its interior throug passageways formed in bearing block 58 and v coupler 67, the water being caused to first flow through the annular cooling chamber formed in bearing sleeve 55. For this pur- 115 pose a water distributing casing 85 may be attached to the rear of, mandrel support and i be connected by a sliding packing gland to a water supply pipe 86. Water from pipe 86 water chamber 88 of-sleeve 55, from which it flows through acasing port 89 into acentral. bore 90 of block 58- which is provided with a The forward end of block 58 is'provided j tubular extension rotatably mounted in ,a

pipe 86 is connected tohousing 32 and communicates with a passageway- 91 formed in the housing, which passageway-in turn communicates at its inner end with the inner end of passageway92 formed injtrun nion' 3 a mandrel head 101.

outlet passage for rearward flow of water. From tlns annular passageway'water flows through ports 96 at the inner end of mandrel bar G, ports 97 at the outer end ofcoupler 67 and ports 98 in mandrel bar support-31.

Having reference now to Figs. 9 and 10, the outer end of mandrel bar 6 is shown as having attached to it a holder 100 provided with This holder preferably has a sleeve 102 provided with an ex-.

ternal tapered thread adapted to receive an internal thread formed at the outer- .end of mandrel bar 6, the holder being provided exteriorly with holes or sockets 106 for engage ment by a bar or spanning wrench for connecting the holder to or disconnecting it from the bar. Spanner wrench holes "106 are located at a position on the mandrel head where the pierced portion of a billet clears the surface, of the head. The inner end of sleeve 102- is provided internally with a series of projections 103 for receiving the outer end of tube 95, the 'ends of these projections being chamfered as indicated so that when the .mandrel holder is applied to 'themandrelbar the outer contracted end of tube 95 may he easily positioned at the center of sleeve 102 and concentrically within the mandrel bar. Cooling water flowing lon itudinally within tube 95, passes around is end, and then flows outwardly through the spaces formed betweenproj ections'103 and the outer face of the tube as indicated by arrows105.-

The water then flows-rearwardly on the outside of the tube 95, .and escapes at the inner end of-the mandrel barthrough the several ports explained above.. To the end that the cooling water may effect a maximum absorption of heat from the mandrel bar, tube 95 is of such size that there is a relatively small space between its exterior and the interior of the bar. .In this way a rapid rearward flow of water is effected adjacent to the mandrel sorption.

bar with a correspondingly large heat ab- Inusing mandrel heads such as shown in Fig. 10 they become so heated during a piercing operation that it is generally necessary to replace them,be'tween piercing operations.

" The piercing mill, herein disclosed is espe- -cially well adapted for this because the heads may be changed in the interim between piercings on the respective 'mandrelsa However, onefeature of this invention has to do with thelprovision of a watercooled mandrel which need not be removed, the preferred construction being that illustrated in -Fig. 11. As there shown, a mandrel 110 is provided with a central cavity 111, and central tube 112 of mandrel bar 6 is provided with an extension tube 114 projecting substantially to the end of this cavity. The inner end of extension tube 114 is engaged exteriorly' by a ring 115 which fits fairly loosely within tube 112, and which is provided exteriorly with an expansible packing ring 116. The inner end of mandrel 110 is.

provided exteriorlywith a tapered thread v to engage an internal tapered thread formed at the end of mandrel bar 6', and is-provided with a sleeve 117 having projections 118 formed on its outer face to support the outer end of tube 112 and at the same time permit I a starting point that its parts are in the positions' generally indicated in Fig. 1, a billet 21 is placed-with its entering end uponbillet supporting roller 10, the outer end of mandrel 5 being supported by bracket 11 held in its upper position by admitting pressure fluid to cylinder 18 to raise rod 16, and the inner end of the mandrel bar being-supported by the spherical head 66 ofcoupler 67. 'Roller 10 and bracket ll thus position billet 21 and mandrel 5 in such positionwith relation to each other and to the pass between the piercing rolls, thatth'e end of the mandrel head will enter the center of the billet. The center line of the pass or billet is preferably below the narrowest space between the main rolls thus thrusting the billet against its supporting roll 10. As the piercing rolls :are rotated and the piercing operation progresses, pressure fluid is exhausted from cyl- 1nder 18 to permit bracket 11 to move downwardly out of the ath of the pierced portion of the billet. uringthe piercing operation, water is caused to flow through mandrel bar 5, and also through the mandrel head in case mandrel head of Fig. 11 is attached to the end of the bar. The line of fiowof cooling water is from casing 85 through passageway 90 in block 58, and then through coupler 67 and mandrel bar tube 95 to the outer end of the mandrel bar. It then flows rearwardly on the outside of tube 95 and escapes through ports 96, 97 and .98. As

the rear end of the billet passes over the mandrel head the collars shown at the ends of the piercing roll continue to rotate and feed the .pierced billet over the mandrel bar until the piefced billet is moved entirely beyond the At the end of the' .piercing operation,

motor 42 is set in operation for swinging the mandrel upwardly with the pierced billet surroundingthe mandrel bar, and when this mandrel is clear of the piercing rolls and their housing, motor 28 (Fig. 5) is operated to move carriage 1 transversely to bring mandrel bar 6 in a position to belowered between the piercing rolls. While the mandrels are so moved each is supported at its inner end by the spherical head 65 on coupler 67 and by flange 84 of ring 69 which then rests upon flange 83 of ring 77 (Fig. 8). Continued operation of motor 42 for raising mandrel 5 causes such mandrel to swing to the opposite side of the mandrel carriage in a position for stripping the pierced billet from it by suitable mechanism provided for this purpose and which is not shown. While the stripping of the billet from mandrel 5 is in progress, the piercing of another billet .upon the mandrel head at the end of mandrel bar 6 simultaneously takes place.- This operation is repeated at the completion of the piercing ,of each billet, carriage 1 being alternately moved backwardly and forward-. ly transversely of the line of feed through the piercing rolls, and motors 42 being operated to swin the mandrels alternately to and from bi let-piercing and mandrel-stripping positions. By the use of this mechanism, the piercing rolls may be operated substantially continuously so that 'an adequate suppl of pierced billets may be supplied to a tu e forming mill.

For adjusting'each mandrel bar support in its housing to properly position the end 0 its attached mandrel head for a piercing operatiomhand wheel 53 (Fi 7) is turned to rotate screws 45. ,It will be understood, however, that such adjustment is not required for each piercing operation, but usually only when adjusting thevmill for forming different sized pierced billets. The rotation of the mandrel bar consequent upon the action of the piercing rolls is transmitted through mandrel bar coupler 67 to block 58 which is rotatablymounted within water-cooled sleeve 55. The lateral movement of the outer end of the mandrel during the piercing operation is madefefleotive from the center of spherical 'head 66 at the inner endof coupler 67 so may be practiced by other forms of mills and 'by mills embodying other details of construc tion than particularly .shown and described. I I claim as my invention:

1. Ina billet-piercing mill, the combination with a set of piercing ,rolls, of a plurality or mandrel supports associated with said rolls and each independently movable alternately in opposite directions to and from piercing and stripping positions whereby piercing and stripping operations may be simultaneously conducted. 2. In a billetiercing mill, the combination with a set o piercing rolls, of a mandrel carriage movable transversely of the line of feed of a billet between said rolls, and a plurality of mandrels supported by said carriage for independent movements, whereby one mandrel may be moved to and held in piercing position while another mandrel may be moved from piercing to stripping position.

3. In a billet-piercing mill, the combination with a set of piercing rolls, of a mandrel carriage movable transversely of the line of feed 0 a billet between said rolls, a plurality of mandrel bars provided at their outer ends with mandrel heads and having their inner ends supported by said carriage for independent vertical swinging'movements, whereby one mandrel may be moved to and held in piercing position while-another mandrel may be moved from piercing to stripping position.

4. In a billet-piercing mill, the combination with a set of piercing rolls, of a mandrel carriage movable transversely of the line of feed of a billet between said rolls, a pair of mandrel bars provided at their outer ends with mandrel heads and having their inner ends supported by said carriage for vertical swinging movements, means for effecting said f transverse movements of the carriage, and

carriage movable transversely of the line of feed of a billet between said rolls, a plurality'of mandrel supports eachmounted on said carriage on an axis for independent vertical swinging movements, motors borne by said carriage, and driving connections from each motor to each mandrel support for swinging it.

' 6. In a billet-piercingmill, the combination with aset of piercing rolls, ofa mandrel bar support "housing, a mandrel bar support mounted in said housing for longitudinal adjustment with relation. toit, a plurality of screws connecting said support-with said housing,and means forsimultaheously rotat ing said'screws tomove the support with relation to the housing.

Ill

7.'In a billet-piercing mill, the coiubination with a set of piercing rolls, of a mandrel bar support housing rotatably mounted. on a horizontal axis for vertical swinging movement, :1 mandrel bar support mounted in said housing for longitudinal adjustment with relation to it, a plurality of screws connecting said support with said housing, and means for simultaneously rotating said screws to move the support with'relation to the housing. 8. In a billet-piercing mill, the combina-v tion with a set of piercing rolls, of a mandrel bar support housing rotatably mounted on a horizontal axis for vertical swinging movements, a mandrel barsupport mountedin said housing for longitudinal adjustment with relation to it, a mandrel coupler having at its inner-end a universal joint connection to said support, a mandrel bar, and

means for rigidly attaching the rear end of said'bar to the outer end of said coupler.

9. In a billet-piercing mill, the combination with a'set of piercing rolls, of a'mandrel bar support housing rotatably mounted on a horizontal axis for vertical swinging-movements, a mandrel bar support mounted in sald housing for longitudinal ad ustment with relation to it, means for effecting said,

longitudinal adjustment, a coupler having at ,its inner end a universal joint connection with said support, a mandrel bar, and m ans for rigidly attaching the rear end ofsai bar I to the outer end of said coupler, the outer end of said support beingprovided with means for. engaging'the outer end of said coupler permitting lateral movement of the outer .end

of the coupler in all directions.

10. In a billet-piercing mill, the combination with a set of piercing rolls, of a mandrel bar support housing rotatably mounted on a horizontal axis for vertical swinging movements, a mandrelbar supportmounted for longitudinal adjustment in said housing, a mandrel coupler pivotally connected at its inner end.to said housing for universal lateral-move'mentsof the outer end of the cou pleriwithrrelation to the housing, atubulan mandrelbar rigidlyconnected to the outer end of said -'support, and cooling fluid pas sageways extending. through said housing support and coupler for introducing cooling fluid into said mandrel bar.

.11. In a billet-piercing mill, the c0mbination with a set of piercing rolls, a mandrel comprising a bar provided at its forward end .with a'mandrel head, and means for supporting the rear end of said bar; of

' means for supporting the'forward' end of said maindrel at the beginning of a piercing operati'onin proper position for said mandrel head to enter the end of-a billet to be pierced, said last-namedemandrel supporting means being movable by the movement of a,billet being pierced out of the path of its pierced portion. 3

of a billet bei-n its pierced portion.

P r ed portion.

means for supporting in the piercing pass of said rolls the entering end of a billet to he pierced, and means for supporting at the beginning of a piercing operation the forward end of said mandrel in a position. for entering the center of an end of a billet to be pierced, said last named mandrel supporting means being movable by the movement pierced out of the path of -13. In a billet-piercing'rnill, the combination wit-ha set of piercing rolls, a. mandrel comprising a bar provided at its forward end i with a mandrel head, and means for supporting the rear end of said bar, of a roller mounted on a horizontal axis transverse to the line. of feed through said rolls and arranged below the piercing pass of said rolls for supporting the forward end of a billet to be pierced, and means for supporting at the be ginning of api'ercing operation the forward end of said man'drel in a position for entering the center'of an end of a billet to be pierced, said last-named mandrel supporting means being movable by the movement of a billet being pierced out of the path of its 14. In a billet-piercing mill, the combina'-- tion with a set of piercing rolls, a mandrel comprising a bar provided at-its forward end with a mandrel head, and means for supporting the rear end of. said bar ofmeans for supporting the forward end of a billet to be pierced, and a. bracket movable to a pos'tion-for supporting at the beginning of a piercing operation the forward end of said mandrel at the center of the entering end of a billet to be pierced, said bracket bei. ing subsequently movable by the movement of abillet being pierced from said position out of the'path of the-pierced portion of the billet. 15. In a billet-piercing mill, the "combination with a set of piercing rolls, a mandre comprising a bar provided at its forward .end.

with a mandrel head, andmeans for supporting the, rear end of said bar; of means for supporting the forward end of a billet to be pierced, a vertically movable bracket forsupporting at the beginning of a piercing operation the forward end of said mandrel in position for entering the center of the end of a billet "to be pierced, and releasable means for holding said bracket in said position. U 1.6. In a billet-piercing mill, the combination with a set of piercing rolls, a mandrel comprising a bar provided at its forward end with a mandrel head, and. means .for supportingthe rear end' of said bar; of means far supporting the-forward end of'jabilletj 139' ward end of said mandrel in position for entering the center of the end of a billet to-be pierced, and power-actuated mechanism ior moving and holding sald bracket m said position.

17. In a billet-piercing mill, the combination with a set. of piercing rolls, a mandrel comprising a bar provided at its forward end with a mandrel head, and means for supportingthe rear end of said bar; of a roller rotatably mounted on" a horizontal axis tranverse to the line of feed through said rolls and arranged below said rolls for supporting the forward end of a billet to be pierced, a bracket rotatably' mounted on the axis of said roller for supporting at the beginning of a piercing operation the forward end of said mandrel in a position for, entering the center of a billet to be pierced, and poweractuated mechanism for moving and holding said bracket in said position.

18. In a piercing mill, the combination with a set of piercing rolls, and a mandrel support; of a tubular mandrel bar attached at its rear end to said support, a mandrel head provided With a concavit detach-ably connected to the outer end 0 said bar, a tube extending concentrically through said mandrel bar from its rear to its forwardend,

and a second tube telescoping With and extending from the forward end of said first- I mentioned tube into the concavity of said mandrel head, said tubes forming a passage- Way for the circulation of fluid through their interior and between their exterior surface and the interior Walls of the mandrel bar and mandrel head, for cooling the mandrel bar and head.

In testimony whereof, I sign my name.

SAMUEL E: DIESGHER. 

